The assembly of rotor blades on wind turbines and their transport to and fro is a time-consuming, relatively dangerous and also costly task. Prior blade gripping devices often consist of a frame (also referred to as yoke) and a number of straps which are wound around at least part of the rotor blade to hold the rotor blade in place. This involves a lot of manual assistance: the frame has to be directed towards the rotor blade very exactly so that the rotor blade fits into the frame. Further, the straps have to be wound around the rotor blade and also unwound manually which involves work at substantial heights. Technicians are typically raised to the assembly height by a basket from which they operate during the assembly or disassembly of the rotor blade.
International patent application WO 2011/050999 A1 shows a solution of a dismounting system for a rotor blade of a wind turbine. The system comprises a stable main frame and an automatic strap moving mechanism connected to the main frame. The strap moving mechanism leads the strap around the rotor blade by means of a number of beams that temporarily hold an end portion of the strap to lead it from one side of the rotor blade to the other side. For that purpose, the beams are tilted in several tilting directions in order to eventually encompass the rotor blade partially. A camera control system controls the engaging of the strap in an engaging position.
Such dismounting system is still rather complex to handle.